用新的紫外荧光光源对维生素D_2的最佳光合成

介绍了维生素 D2 (以下简称 VD2 )的光化反应与光照时间的关系 ,即由麦角甾醇为原料 ,在与之转化所需的最佳匹配光谱照射下 ,找到 VD2 的最佳光转化时间。结果表明 ,在 2 83 nm波长的紫外荧光光源照射下 ,其转化效果最佳。在此条件下麦角甾醇转化率随照射时间的增加而逐渐上升 ,但同时 VD2 的异构体 (副产物 )也随之增多 ,因此综合以上两种因素 ,从而可确定 1 8～ 2 1分钟是 VD2 光化反应的最佳时间段。     

VO2薄膜对TEACO2激光响应特性的实验研究

报道了ＶＯ２薄膜在ＴＥＡＣＯ２激光照射下的相变特性的实验研究，结果表明：对于本文镀制的ＶＯ２薄膜，在偏置温度为５２℃条件下，ＴＥＡＣＯ２激光入射能量密度为１５０ｍＪ／ｃｍ＾２时，可使ＶＯ２薄膜发生相变，响应时间，５０ｎｓ，恢复时间≈２００μｓ。     

H2和CO在Pd（110）上的吸附和共吸附

应用ＸＰＳ，ＵＰＳ，ＬＥＥＤ和ＴＤ研究了ＣＯ和Ｈ２在Ｐｄ（１１０）上在室温下的吸附与并吸附。ＣＯ在Ｐｄ（１１０）上随暴露量增加至饱和，吸附位由β１态向β２态变化，相应的ＸＰＳＣ（１ｓ）峰由２８５．３ｅＶ向高结合能方向位移至２８５．７ｅＶ。     

Br^—2,Cl^—2.诱导氧化磷酰化甲硫氨酸水溶液的脉冲辐解研究

采用脉冲辐解动态吸收光谱法研究了Ｂｒ＾－２和Ｃｌ＾－２自由在诱导氧化Ｎ－二异丙基磷酰化甲硫氨酸（ＮＤＭ）水溶液的过程，结果表明：Ｂｒ＾－２和Ｃｌ＾－２进攻ＮＤＭ中的硫原子形成含硫三电子键ＮＤＭ（Ｓ∴Ｘ）（Ｘ＝Ｂｒ，Ｃｌ）它们分别在４００ｎｍ和３９０ｎｍ处有最大吸收峰，形成和衰变均呈一级反应，测定了不同条件下氧化反应的速率常数，推导了反应机理，并从分子结构观点与甲硫氨酸水溶液的Ｂｒ＾－２．Ｃｌ＾－２     

MOCVD法在金属基体上制备YBCO超导带

本报道了用ＭＯＣＶＤ静态和动态沉积两种工艺制备ＹＢＣＯ超导带的实验结果。以Ｙ（ＴＭＨＤ）３、Ｂａ（ＴＭＨＤ）２和Ｃｕ（ＴＭＨＤ）２为挥发源，Ｏ２气为反应剂，高纯Ａｒ气为载流气体，在静止和以１０－１５ｃｍ／ｈ带速移动的金属银基体上，制出了有强烈ｃ－轴取向的ＹＢＣＯ超导带。静态沉积样品的Ｊｃ达到１．０４×１０＾４Ａ／ｃｍ＾２，动态沉积样品的Ｊｃ达到１．４×１０＾４Ａ／ｃｍ＾２（７８Ｋ，０Ｔ）。对改…     

用含时波包理论处理HD＋H→H＋DH,D＋H2反应

用含时波包（ＴＤＷＰ）理论计算了具有两个不同产物道的反应ＨＤ＋Ｈ→Ｈ＋ＤＨ，Ｄ＋Ｈ２的初态确定的反应几率及生咸物的分支比。在利用分解算符法进行波包传播的过程中，采取了分立变量表象（ＤＶＲ）及分立交量－有限基表象（ＤＶＲ—ＦＢＲ）变换，这一方法降低了传播过程中需保存大变换矩阵的要求。通过应用能量投影法，可从单一波包中抽出许多能量确定的动力学信息。为了避免因所选取的格点范围有限而引起的波函数在边界点附近的反射，传播过程中还采用了光学势以吸收反射波函。     

原子簇H4构型的稳定性

本文用多重散射Ｘα方法对Ｈ４的正方形（Ｄ４ｈ）９正四面体Ｔｄ），正三边形（Ｄ３ｈ），正三棱锥（Ｃ３ｖ），菱形（Ｄ２ｈ），矩形（Ｄ２ｈ）Ｄ２ｄ和Ｄ２等几何构型进行了研究，得到了这些构型在稳定性相对顺序，并分析了有可能成为交换反应：Ｈ２＋Ｄ２→２ＨＤ中过滤态的前五种构型，最终不能成为过滤态的原因。     

H2O＋Cl→HCl＋OH反应中D同位素的动力学效应的理论研究

根据传统过渡态，变分过渡理论计算了Ｈ２Ｏ＋Ｃｌ→ＨＣｌ＋ＯＨ（Ｒ１）反应中Ｄ代替的同位素动力学效应（ＫＩＥ）得到了ＨＯＤ＋Ｃｌ→ＤＣｌ＋ＯＨ（Ｒ２），ＤＯＨ＋Ｃｌ→ＨＣｌ＋ＯＤ（Ｒ３）反应不同的ＫＩＥ值，对ＫＩＥ进行了分解，讨论了平动（ｔｒａｒｓ）转动（ｒｏｔ）振动（ｖｉｂ）等各种因素的作用，在反应Ｒ２中，由于ＨＯＤ中ＯＤ键直接参与反应，Ｄ同位素的ＫＥ很大，对Ｒ２的ＫＩＥ分解表明，振动对ＫＩＥ贡献     

d^3络合物零物分裂的双自旋—轨道耦合参数模型

建立了三角对称ｄ＾３络合物零场分裂的双自旋－轨道耦合参数模型，它包括了经典晶场模型的零场分裂公式所忽略的配体贡献Ｄ（ζｐ）以及配体与中心离子相互耦合贡献Ｄ（ζｄ，ζｐ）的两部分；讨论了在不同的ζｐ，ζｄ及λｒ的情况下Ｄ（ζｐ）及Ｄ（ζｄ，ζｐ）的相对大小；指出了在ζｐ及λｒ较大的情况下双自旋－轨道（ＳＯ）耦合参数模型才能给出合理的结果；作为该模型的应用，计算了ＶＣｌ２和ＶＢｒ２的零场分裂，验证了Ｄ     

硅（磷）中心自由基与2─丁烯二酸二乙酯的加合反应机理

用ＥＳＲ方法研究了硅（磷）中心自由基与２－丁烯二酸二乙酯的加合反应机理．具有顺式构型的马来酸二乙酯（ＤＥＭ）与硅（磷）中心自由基反应，生成自由基加合物。ＤＥＭ的聚合反应受到抑制。具有反式构型的富马酸二乙酯（ＤＥＦ）易发生聚合反应，ＤＥＦ与硅（磷）中心自由基的加合反应受到抑制．ＤＥＦ与ＤＥＭ在反应性能上的差异，主要来自ＤＥＦ有较大的空间位阻效应．     

Titania Gold Composite: Effect of Illumination on Size of Gold Nanoparticles with Consequent Implication on Photocatalytic Water Splitting

This work deals with the study of photodeposition (PD) of gold nanoparticles (AuNPs) on TiO₂ by using different illumination sources, Medium pressure Mercury lamp (ML), Solar Simulator equipped with AM 1.5 (SL) and Tungsten lamp (WL). Different particle size of AuNPs on TiO₂ were obtained by photodeposition method under different illumination sources, which clearly proves the influence of light source on the synthesis of Au–TiO₂. The plasmonic activity of Au–TiO₂ photocatalyst for water splitting reaction was observed to be strongly influenced by the particle size of Au as well as illumination source. Amongst the three different illumination sources used, smallest particle size for AuNP–TiO₂ were observed under ML followed by SL and WL, as revealed by TEM analysis. Different illumination sources were also investigated to evaluate the activity of Au–TiO₂ samples thus prepared under different illumination conditions. The order of hydrogen evolution rate (HER) observed for Au–TiO₂ with different source of illuminations is ML > SL > WL. The highest HER of 1709 μmol/h was observed for Au–TiO₂, which was synthesized and evaluated under ML irradiation. This may be explained on the basis of reduced catalytic activity and photothermal effect of Au nanoparticles with increasing particle size.     

Daylight perceptive lighting and data fusion with artificial neutral network

The basic concept of daylight perceptive is that the artificial light automatically dims to the appropriate level to keep constant indoor illumination when sufficient daylight is not available. Energy efficient character of daylight perceptive lighting was analyzed and a method to evaluate energy saving was present; according to the presentation, the more energy is saved if the longer T_last—duration of indoor illumination being is less than threshold. A daylight perceptive controller was developed and the output power of LED light source under different PWM was measured, according to the measurement, work current and output power of LED is proportional to duty cycle. With two sensors, a data fusion method was put forward to exclude interference and improve lighting comfort. With more than two sensors, data fusion based on neutral network was discussed.     

Modulation instability with incoherent white light in self-defocusing photorefractive crystal

We report on the first experimental observation of modulation instability and spontaneous pattern formation with incoherent white light emitted from an incandescent lamp in self-defocusing photorefractive LiNbO₃:Fe crystal. Experimental results show that the modulation instability of white light in self-defocusing medium is related to the input intensity, illumination time and the direction of the crystalline c-axis with respect to that of the lamp filament. At the illumination time t = 0 and the steady-state of MI, we give the spatial distribution of the optical Fourier power spectrum experimentally and the corresponding Fourier transformation of the output intensity numerically, and observe the emergence of the high frequency component along the c-axis.     

SiO_2胶体晶体自组装技术

介绍了垂直沉降法和旋涂法制备SiO2胶体晶体,并对两种方法制备的胶体晶体在宏观形貌、微观结构及光子带隙性质进行了比较。采用改进的Stober法在乙醇介质中合成粒径不同、单分散性较好的SiO2微球,用垂直沉积法和旋涂法制备出有序性较好的密排结构的SiO2胶体晶体。宏观照片表明,用旋涂法制备的SiO2胶体晶体经白光照射出现的光柱呈6次对称,而垂直沉降法制备的胶体晶体表面出现条纹。SEM分析表明,选用不同溶剂在同等旋涂工艺下制备SiO2胶体晶体,用乙醇和乙二醇混合溶液作溶剂制备出的SiO2胶体晶体质量最好。透射光谱表明,垂直沉降法所制备的胶体晶体在(111)方向具有明显的光子带隙性质,而旋涂法制备的胶体晶体则不明显。     

TiO2–carbon nanotube composites for visible photocatalysts – Influence of TiO2 crystal structure

We investigated the influence of the crystal structure of TiO₂ and the use of different TiO₂ precursors on the properties and photocatalytic activity of carbon nanotube (CNTs)–titania composites. We found that the crystal structure and properties of starting TiO₂ nanomaterial significantly affected the effect of CNTs incorporation on the photocatalytic activity under simulated solar and visible light illumination (simulated solar illumination with UV-blocking filter). In case of significant photocatalytic activity under visible light illumination (anatase TiO₂), likely due to the presence of native defects, composites exhibited lower activity under visible illumination only, but higher activity under simulated solar illumination. The opposite trends were observed for P25 (anatase + rutile) and rutile TiO₂, where incorporation of CNTs resulted in a significant increase of photocatalytic activity under visible illumination. Thus, control over crystal structure and native defects is essential for the development of efficient visible light activated photocatalysts.     

Simple sonochemical synthesis of Ho2O3-SiO2 nanocomposites as an effective photocatalyst for degradation and removal of organic contaminant

In this work, highly photocatalytically active Ho₂O₃-SiO₂ nanocomposites have been designed and applied for decomposition of methylene blue pollutant. Ho₂O₃-SiO₂ nanocomposites have been produced by new, quick and facile sonochemical process with the aid of tetramethylethylenediamine as a novel basic agent for the first time. The effect of the kind of basic agent, ultrasonic time and dosage of Ho source on the grain size, photocatalytic behavior and shape of the Ho₂O₃-SiO₂ nanocomposites have been evaluated for optimization the production condition. FESEM, EDX, FT-IR, DRS, XRD and TEM have been applied to characterize the as-produced Ho₂O₃-SiO₂ nanocomposites. Use of the as-produced Ho₂O₃-SiO₂ nanocomposites as photocatalyst via destruction of methylene blue pollutant under UV illumination has been compared. It was observed that SiO₂ has notable impact on catalytic activity of holmium oxide photocatalyst for destruction. Introducing of SiO₂ to holmium oxide can enhance destruction efficiency of holmium oxide to methylene blue pollutant under ultraviolet light.     

Additive coloring of CaF<Subscript>2</Subscript> optical ceramic

The specificity of additive coloring of CaF₂ optical ceramic (formation of color centers in it and photothermochemical transformation of these centers in colored ceramic samples) has been considered. Under the same coloring conditions, this process occurs more slowly in ceramics rather than in crystals; at the same time, the limiting concentration of color centers that can be introduced into ceramics is much higher. The photothermochemical transformations of color centers in crystals and ceramics, which occur under illumination at different wavelengths and upon heating, have been studied. The specific features of introduction of color centers into ceramic and their transformation under illumination and heating are likely to be related to the mass twinning of ceramic grains.     

Photoplasticity of As2Se3 films investigated with combined nanoindentation and AFM methods

Thin As₂Se₃ amorphous chalcogenide films have been studied by nanoindentation and atomic force microscopy in darkness and under illumination by band-gap light. The combination of these two methods has been used to study the peculiarities of the photoplastic effect in amorphous semiconductors. It has been shown by multiple loading indentation experiments that a non-linear mechanism of the formation of the strain response is realized in the As₂Se₃ films subjected to the combined action of light and external mechanical loading. We have observed that light illumination alters the internal friction of the films and their shear modulus. These observations have been considered in the frame of the two-phase model of chalcogenide glasses. Some arguments in favor that the self-organization processes take place in the structure of irradiated film are given.     

Photoelectrical memory effect in ZnIn2Se4

The compound ZnIn₂Se₄ with n-type conductivity is shown to exhibit electro-optical memory effect and negative resistance effect similar to those previously reported for ZnIn₂S₄. At low temperature ZnIn₂Se₄ material will present a high conductivity during and after illumination by light of energy greater than the band gap. This high conductivity state can be quenched in three different ways (i) by heating the sample until it reaches room temperature, (ii) by illumination with monochromatic light of appropriate energy, (iii) by an electric field. In the latter case the material exhibits a negative resistance effect in the transition between the low and high conductivity conditions. These charge storage phenomena have been explained by assuming the presence of a level, localized in the forbidden gap, which is twofold negative charged and presents a repulsive barrier to the recombination of electrons.